1. Field of the Invention
The present invention relates to a cylindrical member constituting a main body of a photosensitive drum, a developing sleeve or the like, adapted for use in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, a facsimile apparatus, a printing apparatus employing electrophotographic process, and also to a method for producing the same.
2. Related Background Art
The photosensitive drum or developing sleeve employed in the electrophotographic image forming apparatus such as copying machine, laser beam printer, facsimile apparatus, printing apparatus or the like has conventionally been based on a cylindrical member which is finished to a predetermined surface roughness. The electrophotographic photosensitive drum is produced by applying a photosensitive film onto the surface of such cylindrical member finished to a predetermined surface roughness, so that a deficiency in the surface precision or dimensional precision of the cylindrical member results in surface irregularity of the photo-sensitive film, causing a defect in the image formed by the image forming apparatus. Consequently, for producing an image forming apparatus of a high accuracy, there is required a cylindrical member which is extremely accurate in the straightness and roundness.
A cylindrical member of high surface precision, straightness and roundness is required also for the developing sleeve which is used, in developing a latent image formed on the photosensitive film by an electrophotographic process or an electrostatic recording process, for supporting and transporting developer of various types, such as one-component, two-component, magnetic, non-magnetic, insulating or dielectric developer.
The cylindrical member for such electrophotographic photosensitive drum or developing sleeve is generally composed of Al of a purity of 99.5% or higher, or an aluminum alloy such as a Cu-Al alloy containing Cu in 0.05 to 0.20%, a Cu-Mn-Al alloy containing Cu in 0.05 to 0.20% and Mn in 1.0 to 1.5%, a Si-Mg-Al alloy containing Si in 0.20 to 0.60% and Mg in 0.45 to 0.90%, or a Mn-Al alloy containing Mn in 1.0 to 1.5%. For producing the above-mentioned cylindrical member with such material, there have been developed, for example, a method of preparing a tube of high surface precision and dimensional precision by highly precise extrusion, drawing and bending correction, cutting the tube by a desired length and finishing the internal surface of both ends by cutting, and a method of cutting a pipe, prepared by extrusion and/or drawing, by a desired length, cutting the internal surface of both ends and finishing the curved surface by a cutting tool (Japanese Patent Laid-open Application No. 2-110570).
However, in such conventional technologies, the former method preparing a pipe of high surface precision and dimensional precision by extrusion, drawing and bending correction, then cutting the pipe by a desired length and cutting the internal surface of both ends is associated with a high manufacturing cost of the pipe member, because highly precise control is required in the steps of bending correction or the like. Also, the later method of cutting a pipe of low cost, prepared by extrusion and/or drawing, and rotating the cut pipe (hereinafter called "work") to finish the curved surface, tends to result in vibration of the work when it is rotated at a high speed in the cutting step, because of unevenness in thickness of the work, deficient straightness of the work or insufficient precision of the internal diameter at both ends. For this reason, the revolution of the work has to be limited to about 3,000 rpm, so that it is difficult to shorten the time required for the cutting step. Besides, the motor has to be stopped when the work is attached to or detached from the cutting machine, and there is required a long waiting time for the starting-up of motor in each working cycle of the work. As a result, the entire process cycle time becomes longer, and the manufacturing cost becomes inevitably higher.